The present invention relates generally to coaxial connectors for connecting, and more particularly, to coaxial connectors for use at relatively high frequencies.
Coaxial connectors are used as means to transmit electrical signals from one electronic device to another electronic device, from the electronic device to a coaxial cable, or from a coaxial cable to another electronic device. Often, hermetically sealed coaxial connectors are needed to minimize adverse effects of environmental factors such as humidity to the electronic device that the connector is connected to and thus to the electrical signals carried by the device. This is especially true for relatively high frequency signals such as microwave signals.
FIG. 1A illustrates a perspective exploded view of a prior art connector 10 and FIG. 1B illustrates a cutaway side view of the connector 10. The connector 10 includes an outer conductor 12 (also referred to as a barrel) having generally a cylindrical tube shape running along a longitudinal axis 13 and a subassembly 11. The connector 10 has an external end 14 and a connection end 16 opposite the external end 14. The external end 14 defines an outer conductor reference plane 15 illustrated by reference plane line 15.
The outer conductor 12 houses the subassembly 11. The subassembly 11 includes a center conductor 18, a sleeve 24 of conductive material, and a spacer bead 17 of insulator material. The center conductor includes a solid portion 18a and a fingered portion 18b. For convenience the center conductor portions 18a and 18b of the center conductor are collectively referred to as the center conductor 18. A glass to metal seal (GMS) assembly 22 includes a center pin 20 surrounded by glass seal 23 and a conductive annular ring 27. The subassembly 11 runs coaxially with the axis 13 of the outer conductor 12. The center pin 20 extends beyond the connection end 16 to allow the center pin 20 to mate with a device or a circuit.
The center conductor 18 extends to and ends proximal to the outer conductor reference plane 15, the end of the center conductor 18 is illustrated by line 19 in FIG. 1. Distance 21 between the outer conductor reference plane 15 and the end of the center conductor 18 is called pin depth 21. Pin depth tolerance is specified by a connector standard. For example, it is common to require the pin depth 21 to be less than 0.05 mm to meet the standard. In addition, there are performance advantages to maintaining a consistent near zero pin depth 21.
The connector 10 is typically manufactured by first assembling the subassembly 11. Then, the subassembly 11 is inserted into the outer conductor 12 until the spacer bead 17 is stopped at a step 26 defined by the outer conductor 12. Next, the pin depth 21 is measured. If the pin depth 21 is outside the desired specification tolerance, the connector 10 is disassembled and reassembled either with a different subassembly 11 or with a shim 25 to adjust the pin depth 21 to achieve the desirable pin depth 21 value. These steps (measure-disassemble-reassemble) may be repeated until the desired pin depth 21 is realized. It would be desirable to minimize or eliminate repetition of these time consuming and costly steps. An alternative is to allow a large variation (greater tolerance) in pin depth 21; however, electrical performance suffers if the pin depth 21 varies over a large range of values.
Accordingly, there remains a need for an improved connector that overcomes or alleviates these problems.